Papua New Guinea’s attorney general has been sacked just hours before lawyers for Prime Minister Peter O'Neill take up a court battle to get a stay on a warrant for his arrest.

O'Neill dismissed Kerenga Kua on Tuesday night after he opposed the government's campaign to narrow the criteria of how prime ministers are elected following a vote of no confidence.

Kua has been replaced by the former foreign minister, Ano Pala.

"It is unfortunate that I've had to take this decision at this time but I must do so in the interests of government and its stability," O'Neill said in a statement.

On Monday it was revealed a police warrant had been issued for O'Neill after a recommendation from PNG's corruption watchdog, Task Force Sweep, amid allegations he authorised about $30m in illegal payments to law firm Paul Paraka Lawyers.

O'Neill has long denied the allegation.

On Tuesday he announced a commission of inquiry into the warrant process, to be headed by Australian judge Warwick Andrew.

The prime minister's lawyers are expected to be in court in Port Moresby on Wednesday morning to try to get a stay on the warrant.

Police have agreed to hold off on following through on O'Neill's arrest until the court makes a decision.

But on Tuesday they renewed their invitation for him to front police headquarters for an interview.

The government is expected to introduce legislation on June 24 to restrict prime ministerial candidates to members of the largest parliamentary party in the event of a no confidence vote.

O'Neill's People's National Congress has the largest party in PNG's 111-member single house of parliament, however, his government is made of a coalition of parties.